Well, I'd certainly love it if you could link to those plugins, because I did some searching and couldn't find anything. Maybe I didn't look hard enough. Anything with leaderboards, social features, multiplayer, etc.

What I'm asking is, what process would you follow to create a social MMO. In regards to the tools I mentioned in my OP, I would like to know how to create a plugin so I can make them work with Construct2, as they could be very useful in creating that type of game.

Firstly, There is a Playtomic plugin, which will be very usefull for storing game stats, but it also has online leaderboards!!!! :D, - http://www.scirra.com/forum/plugin-playtomic-metrics-analytics_topic47142_post295238.html

The actual multiplayer plugin is not out yet, but its being worked on by a amazing user!! - you can follow the tread here: http://www.scirra.com/forum/multiplayer-demo-in-c2_topic47724.html

There is one i used to use before called scoreoid it's really good for making leader boards achievements and notifications ect the leaderboards load allot faster than the ones from plunge playtomic plugin. Scoreoid also allows you to create players and save days for them so they can have profiles inr your game